Indianapolis (8-4) won for the eighth time in 10 games since starting 0-2.
Luck was 19 of 27 for 370 yards and had TD passes of 30, 3, 48, 73 and 79 yards. He broke Peyton Manning's mark for most 300-yard games in one season and joined Manning and Dan Marino as the only quarterbacks to top 4,000 yards in two of their first three seasons.
Washington (3-9) has lost four straight.
Copyright 2014 by The Associated Press